Can I use conditional formatting on a rollup heading?

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I have been trying to find an answer to this simple question: Can I use conditional formatting on a rollup heading?

I have a simple report: a regular data column, followed by two "concat" columns that merge data from other columns together. Only the three columns are visible, and I use rollup on the top two columns. When the data meets a time condition of 86400, I want the text data in the columns to turn red.

I have tried this with both conditional formatting and data exception formatting. It works well both ways for a regular column heading and data, but does not when I change the top two columns to rollup format (the rollup heading does not reformat).